A. Field
The present invention relates to a method for driving a machine comprising at least one periodically moving part and including an electric drive motor which is electrically powered as a function of its specific angular position. The invention also relates to a drive system fitted with a control unit for an electric drive motor.
B. Related Art
A method and a drive system of the above-mentioned kind are known from WO 99/27 426. Because the drive motor continuously applies a preferably constant torque to the described machine the angular speed of the drive motor is a function of said machine's moments of inertia. When said moments of inertia result in speed reduction, the motor adopts the same behavior—just as when the moment of inertia leads to an increase of motor speed. As a result, the fluctuations of the motor's angular speed are exaggerated. In general, such phenomena do not degrade machine operation, for example, as regards the operation of a weaving machine. However there may be a danger that speeds and/or accelerations will be excessive and that damage would follow. There is also a further danger that the speed of the machine will fluctuate so much that synchronization will be lost, for instance with respect to filling insertion with shed formation in air jet looms.